Diffraction grating lens position

[nikosb]

I have a diffraction grating lens that converts a laser beam into the shape of an open circle as shown below:

I was playing around with it using my red laser pointer and I noticed that even if I moved the lens around it still produced the same shape at the same position. That is wether the diffraction gratings lens was centered or off-centered it always gave the same projected image at the same location. Is that normal or does it happen only for the particular shape of an open circie?

I also noticed that even if I reversed the lens it still worked and produced the same shape, at least visually it looked the same but I don't know if it actually changes a little bit. Are diffraction gratings dual faced?

 

[Alaskan]

Interesting, don't know but curious too. Where did you get it?

 

[nikosb]

Interesting, don't know but curious too. Where did you get it?

I got the diffraction gratings on ebay. Just look for Circle Diffraction Gratings

 

[Cyparagon]

Yes, that is all normal. Diffraction gratings work on an interference principle, and are only slightly affected by incidence angle.